Studies on poly(methyl methacrylate)/polystyrene copolymers for potential bone cement applications

The work compares poly(methyl methacrylate-co-styrene) copolymers with virgin PMMA and commercially available controls for potential cementing applications in the areas of orthopaedics, oral surgery, dental implantology and restorative dentistry. Copolymers of poly(methyl methacrylate-co-styrene) were synthesised by suspension polymerisation and characterised using infrared and UV spectroscopy, gel permeation chromatography and viscometry. Particle size of the beads synthesised was found to vary with increasing styrene content. Scanning electron microscopic observations revealed the presence of fine bead like spherical particles. Thermal analysis data showed glass transition temperature (T-g) to rise with styrene content. Melt now index values were found to decrease with increasing styrene content though water content and solubility seems to be unaffected. Incorporation of barium sulphate as a radiopacifier is found not only to improve doughing and setting times but also to have considerable influence in the final compressive strength and exotherm produced during setting. Residual monomer content in the final cement was found to be within acceptable limits.